<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <ul>
    <li><a href="#/home">首页</a></li>
    <li><a href="#/about">关于</a></li>
  </ul>

  <!-- 当 url 变更后，展示对应的代码片段 -->
  <div id="root"></div>

  <script>
    const routes = [
      {
        path: '/home',
        component: () => {
          return '<h1>首页页面</h1>'
        }
      },
      {
        path: '/about',
        component: () => {
          return '<h1>关于页面</h1>'
        }
      }
    ]

    // 要知道url 变更了
    window.addEventListener('hashchange', () => {
      console.log(location.hash)
      renderView(location.hash)
    })

    function renderView(url) { // #/home
      const index = routes.findIndex(item => {
        return ('#' + item.path) === url
      })
      let routerView = document.getElementById('root')
      routerView.innerHTML = routes[index].component()
    }
  
    window.addEventListener('DOMContentLoaded', () => {
      renderView(location.hash)
    })
  </script>
</body>
</html>